In the case where a central processing unit (CPU) writes data to a NAND flash memory in an information processing apparatus, the CPU deletes data within the NAND flash memory and writes the new data. In this case, after the CPU executes a deletion process to secure reliability, the CPU may read data from the NAND flash memory and check whether or not the deletion process is properly executed. This deletion check is referred to as blank check.
In the NAND flash memory, blank data with all bits indicating a logical value “1” is often used as deleted data after the execution of the deletion process. Thus, the blank check is made to confirm whether or not all bits of the data read from the NAND flash memory indicate the logical value “1”.
Regarding flash memories, a flash memory control circuit that deletes stored details in accordance with an auto-erase command, and a nonvolatile memory that repeatedly executes a delete operation and a delete verification operation are known (refer to, for example, Japanese Laid-open Patent Publication No. 11-260075 and Japanese Laid-open Patent Publication No. 2004-134085). A method of executing a delete verification operation on a flash memory device is also known (refer to, for example, Japanese Laid-open Patent Publication No. 2001-176276).